Stabilization of polyvinyl chloride



United States Patent US. Cl. 26045.8 3 Claims ABSTRACT OF THE DISCLOSURE Polyvinyl chloride is stabilized against photoand thermo-deterioration by having incorporated therein at least one compound selected from the l,3,8-triaza-7,7- dimethyl 9,9 disubstituted 2,4 dioxo- [4.5]decane-8- oxyls in a sufiicient amount to prevent such deterioration.

This invention relates to the stabilization of polyvinyl chloride. More particularly, it relates to the stabilization of polyvinyl chloride against the photoand thermodeterioration by having incorporated therein an effective amount of the piperidine-N-oxyl-spiro-hydantoin having the formula HaC I wherein R and R may be the same or different and represent alkyl group or they may be joined together With the carbon atom to which they are attached to form a saturated homocyclic ring or the group of the formula Rs R4 CH CH3 wherein R and R may be the same or different and represent alkyl group.

CH3 CHa Ca CH3 "ice Representative examples of the piperidine-N-oxyl-spirohydantoins (I) which may be employed in this invention include the following hydantoins:

1, 3,8-triaza-7,7,9,9-tetramethyl-2,4-dioxo-spiro [4.5

decane-8-oxyl;

cyclohexane- 1-spiro-2-(6',6'-dimethyl-piperidine-1'- oxyl) -4'-spiro-5"-hydantoin;

(2,2,6,G-tetramethylpiperidinel -oxyl) -4-spiro-2- 6',6'-dimethylpiperidinel -oxyl -4'-spiro-5 hydantoin;

1,3 ,8-triaza-7-n-hexyl-7,9,9-trimethyl-2,4-dioxospiro [4.5 decane-8-oxyl;

1,3, 8-triaza-7-isobutyl-7,9,9-trimethyl-2,4-di0x0- spiro [4.5 decane-S-oxyl;

1,3 ,S-triaza-7,7-diisobutyl9,9-dirnethyl-2,4-dioxospiro [4.5 decane-8-oxyl; and

cyclopentanel -spiro-2- 6,6'-dimethylpiperidine-1 oxyl) -4'-spiro-5 '-hydantoin.

Polyvinyl chloride frequently tends to be coloured and deteriorated with elimination of hydrogen chloride from polyvinyl chloride by action of light and heat. Therefore, the use of an excellent stabilizing agent is usually required in the polyvinyl chloride industry.

There have been heretofore proposed various stabilizers for the protection of polyvinyl chloride against such det-erioration, for example, metallic salt of stearic acid such as calcium-, cadmium-, bariumand lead stearate; organic tin compound such as dibutyl tin laurate and dibutyl tin maleate; 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole; Z-hydroxy 4 n octoxybenzophenone; 1-bis(2- methyl 4 hydroxy 5 tert.-butylphenyl) n-butane and the like.

Although these prior art stabilizers are widely employed in the art, these are not entirely satisfactory to prevent the deterioration of polyvinyl chloride. As a result of our extensive investigations on stabilizers, it has been unexpectedly found that the above-specified piperidine-N-oxyl-spiro-hydantoins of the Formula I exhibit an exceptionally high degree of stabilizing action on polyvinyl chloride against deterioration thereof.

Said compounds are found to have the following characteristic advantages:

( 1) they exhibit a high degree of stabilizing action, as compared with the prior art stabilizers, on polyvinyl chloride against photo-deterioration thereof,

(2) they exhibit a high degree of stabilizing action on all various compositions containing polyvinyl chloride against photo-deterioration thereof,

(3) they show no appreciable degree of colouring action on polyvinyl chloride and can use together with plasticizers and other known stabilizers, without colouring of polyvinyl chloride or weakening of their stabilizing ability,

(4) they show little thermal sublimation and exudation,

(5 they exhibit excellent stabilizing action against thermodeterioration as well as photo-deterioration, although the prior art stabilizers exhibit little or even negative stabilizing action against thermo-deterioration.

It is, therefore, an object of this invention to provide the polyvinyl chloride stabilized against photoand thermo-deterioration by having incorporated therein an effective amount of the piperidine-N-oxyl-spiro-hydantoins of the Formula I.

The term polyvinyl chloride which is stabilized in this invention as used herein means to include monopolymer of vinyl chloride and copolymers of vinylchloride with vinyl acetate or other ethylenically' unsaturated monomers. And, said polyvinyl chlorides may be blended with other resinous polymer such as acrylonitrilebutadiene-styrene resin.

These polyvinyl chlorides and blends thereof may be of any shape or form, for example, powder, filament, fiber, film, sheet and the like.

Where the piperidine-N-oxyl-spiro-hydantoins in this invention are to be employed for the purpose of stabilization, they may be readily incorporated into the polyvinyl chloride by various standard procedures commonly utilized in the art.

The stabilizer hydantoins in this invention may be in corporated into the polyvinyl chloride at any desired stage prior to the manufacture of shaped articles. For example, the dry stabilizer in a form of powder may be admixed with the polyvinyl chloride or a suspension or emulsion of the polyvinyl chloride may be admixed with a suspension or emulsion of the stabilizer of this invention.

The amount of the piperidine-N-oxyl-spiro-hydantoin to be employed in the polyvinyl chloride in accordance with this invention may be widely varied, depending upon the types, properties and particular uses of the poly-vinyl chloride, but the stabilizer of this invention is usually and preferably employed in the range of concentrations of about 0.01-0.5% by weight, these concentrations being based upon the weight of the polyvinyl chloride employed. The hydantoins in this invention may be optionally and advantageously employed alone or in combination with other known stabilizers (including antioxidants and ultraviolet absorbents) such as metallic salt of stearic acid and organic tin compound; fillers; pigments and the like.

If necessary, an optional combination of two or more piperidine-N-oxyl-spire-hydantoins in this invention may be satisfactorily employed in this invention to obtain the better results.

The piperidine-N-oxyl-spiro-hydantoins of the above Formula I are novel compounds unknown in the prior art. These piperidine-N-oxyl-spiro-hydantoins can be readily and advantageously prepared (a) by treating a piperidinespiro-hydantoin compound having the formula 13 A I A (wherein R and R are as defined above) with a peroxide or (b) by reacting a piperidine-N-oxyl compound having the formula (III) wherein R and R are as defined above with an alkali metal cyanide and ammonium carbonate.

4 For the purpose of illustrating the preparation of the piperidine-N-oxyl-spirohydantoins (I) as explained above, some particular embodiments of the preparation of such hydantoins are given below, this disclosure being incorporated herein solely as a reference.

PREPARATION 1 Preparation of 1,3, 8-triaza-7,7,9,9-tetramethyl-2,4-dioxospiro[4.5]decane-8-oxyl To a solution of 20 g. of 1,3,8-triaza-7,7,9,9-tetramethyl-2,4-dioxo-spiro [4.5]decane in ml. of acetic acid was added 0.5 g. of ethylenediaminetetraacetic acid, 0.4 g. of sodium tungstate and then 40 ml. of 30% hydrogen peroxide. The resulting mixture was stirred at room temperature for 7 days. Then, the reaction mixture was concentrated under reduced pressure, and to the residue thus obtained was added a saturated aqueous solution of potassium carbonate and then the resulting mixture was stirred at room temperature for 1 hour. Thereafter, the crystalline substance precipitated was recovered by filtration, washed with water, and then recrystallized from aqueous ethanol to give the desired product melting at 331 C. (decomp.).

Analysis.-Calculated for C H O N (percent): C, 54.98; H, 7.55; N, 17.49. Found (percent): C, 55.19; H, 7.67; N, 17.45.

The electron spin resonance spectrum (in tetrahydrofuran) of the product thus obtained showed a strong I triplet of a hyperfine coupling constant 14.3 oe., which triplet would be given by the splitting due to the interaction of the unpaired electron spin with nuclear spin of the N atom in the piperidine ring. This result evidently demonstrates the presence of a stable N-oxyl free radical in the product.

PREPARATION 2 Preparation of cyclohexane-l-spiro-2-(6',6'-dimethylpiperidine-1'-oxyl)-4-spiro-5"-hydantoin A solution of 1.1 g. of 1-aza-2,2-dimethyl-4-oxo-spiro- [5.5]undecane-1-oxyl, 0.4 g. of sodium cyanide and 2.5 g. of ammonium carbonate in 20 ml. of 50% aqueous ethanol was stirred at 50-60 C. for 7 hours. Then, the reaction mixture was ice-cooled and the crystalline substance precipitated was recovered by filtration, washed with water and then recrystallized from aqueous ethanol to give the desired product melting at 282283.5 C.

Analysis.Calculated for C H O N (percent): C, 59.98; H, 7.91; N, 14.99. Found (percent): C, 59.79; H, 7.82; N, 15.18.

The following examples are given solely for the purpose of illustrating that the piperidine-N-oxyl-spirohydantoins (I) exhibit an excellent stabilizing action on polyvinyl chloride against photoand thermo-deterioration thereof.

In these examples, all parts are given by weight unless otherwise stated.

EXAMPLE 1 In a mortar, with parts of polyvinyl chloride were intimately admixed 1.0 part of lead stearate, each 0.5 part of dibasic lead stearate 2PbO.Pb(C H COO) barium stearate and cadmium stearate and 0.05 part of the piperidine-N-oxyl-spiro-hydantoin in this invention specified in the following Table 1-1.

The resulting powder mixture was compressionmoulded into a sheet of 0.5 mm. thick by rolling at C. for 5 minutes.

For comparative purpose, the polyvinyl chloride sheets were prepared by repeating the same procedure as described above except that the other known stabilizer shown in the following Table 1-1 Was employed instead of the stabilizer of this invention and that the stabilizer of this invention was omitted. In order to test for heat stability of the sheets prepared above, they were heated Th t t lt r ummarized i th foll win Table in Geers oven at 175 C. and the time until the sheets 21.

TABLE 2-l Time, minute Stabilizer 60 80 100 120 Compoundl Colourless Pale yellow.-. Pale yellw Pale yellow. Compound II... do do d v Do. Compound III do Yellow-brown. Control I Brown. Brown. ControlII-.- .do i Pale yellow-.. Yellow Do. None do Brown Black would be coloured and deteriorated was measured. The Furthermore, in order to test for light stability of the results were summarized in the following Table 1-1. sheets which were prepared as above, they were pressed TABLE 1-1 Time, minute Stabilizer 40 60 80 1,3,8-triazo-7,7,9,Q-tetramethyl-2,4-dioxo-spiro[4,51de- Co1ourless. Pa1eyell0w Yellow. Yellow.

cane 8-0xyl (Compound 1)., Cyclohexane-l-spiroQ-(6,6-di-methylpiperidme-1- oxyl)-4-spiro-5-hydantoin (Compound II) (2,2,6,6-tetra1nethylpiperidine-l-oxyl)-4-sp1ro-2"(t,6- dimethylpiperidine-l-oxyl)-4-spiro-5"-hydanto1n (Compound III).

2-(2-hydroxy-5-methylphenyl)benzotriazole (Control I)- Pale yellow Brown Black. 2-hydroxy-4-n-oetoxybenzophenone (Control II) do .d do None o .do do.

Furthermore, in order to test for light stability of the under a pressure of 20 kg./cm. for 4 minutes and then sheetsprepared above they were pressed under a press r exposed to the artificial Weather at 45 C. by means of of 250 kg./cm. for 5 minutes and then exposed to the the weather meter with sunshine carbon prescribed in the artificial weather at 45 C. by means of the weather meter JIS-Z-0230 with sunshine carbon prescribed in the JIS-Z-0230. The time until the sheets would be coloured and de- The time until the sheets would be coloured and deteriorated was measured. teriorated was measured. The results were summarized in the following Table The results were summarized in the following Table 22. 12.

TABLE 1-2 TABLE H Time, hour l i LE Stabilizer 1, 730 stablliw 1,670 2,500 Compound I. Pnt rown. 88358333iijij "'""jjifftiifi fiiijj Z F Compound II D0. Compound III- .do Compound III. d 130- OontrolI do. (clengoh h d g Control IL. do Colourless.

I1 z g "do H Brown 0 B1 ack N Pale brown-.- Brown.

EXAMPLE 2 EXAMPLE 3 In a mortar, with 100 parts of polyvinyl chloride were I intimately admixed 40 parts of dioctyl phthalate as a In a mortar, Wlth 100 parts of polyvinyl chloride were plasticizer, each 0.5 part of cadium stearate and barium intimately admixed 3 Parts of dibutyl tin f l i pa Stearate, 2 parts f 7 (trade name of a liquid of butyl stearate and 0.15 part of the piperidme-N-oxyl- Stabilizer f cadmiumbarium System f t d and spiro-hydantoin of this invention specified in the following sold by Sankyo Yukigosei Co., Ltd., Japan) and 0.05 liable i resultlng powfliell m1Xt11T e Was p part of the piperidine-N-oxyl-spiro-hydantoin in this in- Mon-molded Into a 30ft P Y Y Chloflde Sheet f 0.

vention specified in the following Table 21. The resulting Fhick by rolling at f minutes. For compowder mixture was compression-molded into a soft poly- Paratlve Purpose, the P Y Y ld h ets Were prei l hl i Sheet f 5 mm. thick by rolling at 170 pared by repeating the same procedure as described above for 5 minutes except that the other known stabilizer shown in the fol- For comparative purpose, the polyvinyl chloride sheets T Was p y d n t ad of the stabilizer were prepared by repeating the same procedure as of this lIlVfiI'ltlOIl and that the stabilizer of this invention scribed above except that the other known stabilizer shown was Omlttedin the following Table was employed instead of the In order to test for heat stability of the sheets prepared stabilizer of this invention and that the stabilizer of this above, the and deterwraung tune e measinvention was omitted. In order to test for heat stability ured p y the Same Procedure and ltlon as of the sheets prepared above, the colouring and deterio descflbed 1n the above p e rating time Were measured by employing the same pro- The test results are summarized in the following Table cedure and condition as described in the above Example 1. 31.

TABLE 3-1 Time, minute Stabilizer 45 60 Compound I Pale yellow-.. Pale yellow Pale yellow... Yellow Dark yellow.

Compound II do 0 d d Do.

Furthermore, in order to test for light stability of the sheets which were prepared as above, they were pressed under a pressure of 250 kg./cm. for minutes and then the coloruring and deteriorating time was measured by employing the same procedure and condition as described in the above Example 1.

The test results are summarized in the following Table 3-2.

EXAMPLE 4 In a mortar, with 100 parts of polyvinyl chloride were intimately admixed 40 parts of dioctyl phthalate and 0.1 part of the piperidine-N-oxyl-spiro-hydantoin of this invention specified in the following Table 4. The resulting powder mixture was compression-molded into a sheet of 0.5 mm. thick by rolling at 140 C. for 5 minutes. For comparative purpose, the polyvinyl chloride sheets were prepared by repeating the same procedure as described above except that the other known stabilizer shown in the following Table 4 was employed instead of the stabilizer of this invention and that the stabilizer of this invention was omitted.

In order to test for light stability of the sheets prepared above, the time of discolouring to brown were measured by means of exposing to the artificial weather at 45 C. by means of the weather meter with sunshine carbon prescribed in the J ISZ0230.

Furthermore, in order to test for heat stability of the sheets which were prepared as above, they were tested for the time of discolouring to black under heating at 160 C. in Geers oven. The results was summarized in the following Table 4.

EXAMPLE 5 In a mortar, with 100 parts of polyvinyl chloride were intimately admixed 30 parts of Kaneka B-16 (trade name of acrylonitrile-butadiene-styrene resin manufactured and sold by Kanegafuchi Chemical Industries Co., Ltd., Japan), 0.5 part of cadmium stearate, 0.5 part of barium stearate, 1.0 part of dibasic lead phosphite and 0.5 part of the above-defined Compound I.

The resulting powder mixture was compression-molded into a sheet of 0.5 mm. thick by rolling at 160 C. for 8 minutes.

After the sheets were exposed to the artificial weather at 45 C. for 50 hours by means of the weather meter with sunshine carbon prescribed in the JISZ-0230, they were tested for the tensile impact strength retention according to the method prescribed in the ASTM 13-1822 61T.

The results were summarized in the following Table 5.

TABLE 5 Tensile impact strength Stabilizer: retention, percent Compound I 68 None 21 It will be apparent from the results summarized in the above tables of Examples 1 to 5 that the piperidine-N-oxylspiro-hydantoins (I) of this invention show excellent stabilizing action on polyvinyl chloride against the photoand thermo-deterioration thereof, as compared with those known stabilizers.

What is claimed is:

1. Polyvinyl chloride stabilized against deterioration by light and heat wherein there is incorporated, in a sufficient amount to prevent the deterioration, a compound having the formula wherein R and R may be the same or dilferent and represent alkyl group 2. The polyvinyl chloride according to claim 1 wherein the said compound is selected from the group consisting of 1,3,8 triaza 7,7,9,9 tetramethyl 2,4 dioxo spiro- [4,5]decane 8 oxyl, cyclohexane 1 spiro- 2' (6,6' dimethylpiperidine 1 oxyl) 4' spiro- 5 hydantoin, and (2,2,6,6 tetramethylpiperidine- 1 oxyl) 4 spiro 2' (6 ,6' dimethylpiperidine- 1-oxyl -4-spiro-5"-hydantoin.

3. The polyvinyl chloride according to claim 1 wherein there is incorporated an amount of 0.010.5% by weight, based upon the polyvinyl chloride, of a compound selected from the group consisting of 1,3,8 triaza 7,7,9,9 tetramethyl 2,4 dioxo spiro [4,5]decane 8 oxyl, cyclohexane 1 spiro- 2' (6',6 dimethylpiperidine 1' oxyl) 4' spiro- 5" hydantoin, and (2,2,6,6 tetramethylpiperidine- 1 oxyl) 4 spiro 2' (6',6 dimethylpiperidine- 1'-oxyl) -4-spiro-5 "-hydantoin.

References Cited UNITED STATES PATENTS 2,441,360 5/1948 Kamin 26045.8 3,474,068 10/1969 Murayama et al. 26045.8

DONALD E. CZAJ A, Primary Examiner R. A. WHITE, Assistant Examiner US.- Cl. X.R. 26023, 45.75 

